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Edition 47 13-5
Cold Planers
13
MACHINE SELECTION
Prime considerations in selecting the proper cold
planer model are:
— specifics of work to be done
— type of projects generally done by the contractor
●
City/Urban or Highway/Airport
— desired production capacities
PM102 Cold Planer
The Cat PM102 Cold Planer features compact dimen-
sions and excellent maneuverability ideal for easy opera-
tion in urban applications. Themachine performs controlled,
full-depth removal of asphalt layers in a single pass and
is also capable of concrete removal. The machine is avail-
able with a wheel or track undercarriage and features
four steering modes for high maneuverability.
PM620 and PM622 Cold Planers
The Cat PM620 and PM622 Cold Planers are high-
production, half-lane milling machines with excellent
maneuverability and plenty of power to perform con-
trolled full-depth removal of asphalt and concrete pave-
ments in a single pass. The track-driven machine features
four steering modes for high maneuverability. The PM620
features a 2.0 m (79") cutting width and performs well in
urban environments or in applications where great maneu-
verability is required. The PM622 features a 2.2 m (88")
cutting width and is ideal for high-production applica-
tions such as main line milling.
Cold Planer Characteristics (Highway/Airport)
Highway/Airport work requires high-volume cold
planers. The PM620, PM622 and other high horsepower
half-lane cold planers are being used more on Highway/
Airport projects. Users like to have one machine that can
work successfully on high production jobs then switch
to city/urban applications.
Cold Planer Characteristics (City/Urban)
All Cat cold planers are four-track, front discharge
models. Front discharge cold planers make traffic con-
trol easier in congested quarters. The trucks travel forward
in the same direction as the cold planer. The trucks move
in and out of traffic faster increasing production.
COLD PLANING FUNDAMENTALS
Definition
Cold planing is automatically controlled cold milling to
restore the pavement surface to a specified grade and
slope; remove bumps, ruts, and other imperfections; and
leave a textured surface which can be opened immedi-
ately to traffic or overlayed with new pavement materials.
Production and ToothWear
Because pavement materials vary, so do production
and tooth wear. While predicting the exact production
rate and tooth wear on a particular job is difficult, gen-
eral guidelines are available.
Production depends on the milling rate (the speed at
which the cold planer moves forward). The machine’s
forward speed is determined, primarily, by aggregate
type, asphalt bond strength and depth of cut. When
milling asphalt pavement, the cold planer’s teeth essen-
tially are breaking the bond between asphalt-coated
aggregate, not actually fracturing the aggregate itself. A
pavement made with a mix containing a high percentage
of fine aggregate and a high asphalt content is more dif-
ficult to mill than a pavement with a high percentage of
coarse aggregate.
A dense or fine mix usually requires more power at the
cutting drum, limiting the cold planer’s forward speed.
Decreased speed lowers production, and the tough bond
between the small aggregate particles causes increased
cutting-tooth wear. Lower production and higher tooth
wear result in increased unit costs.
Cutting depth affects power demand at the drum and
helps determine the cold planer’s forward speed. How-
ever, production increases, to a point, as the depth of cut
increases. For example, changing from a 25 mm (1 in)
cut to a 51 mm (2 in) cut slows the machine only slightly
but doubles the amount of material produced.
As the cut increases beyond the machine’s peak-pro-
duction depth, the reduced forward speed begins to off-
set the production gains of the deeper cut. For example,
production at a 152 mm (6 in) cutting depth and slow
speed may be no greater than cutting at a 76 mm (3 in)
depth and a much faster speed.
Considerations in Machine Selection
Cold Planing Fundamentals